Rhamnella brachycarpa (Rhamnaceae), a new species from Hainan Island, China

Rhamnella brachycarpa Z. Qiang Lu & Y. Shuai Sun, a new evergreen woody species from Hainan Island, is described and illustrated. The specimens of this new species have previously been identified and placed under R. rubrinervis (H. Lév.) Rehder, with which it shares evergreen leaves, erect and climbing habits and axillary flowering branches with bracteole leaves. However, the specimens from three distinct Hainan populations significantly differ from those of R. rubrinervis from other regions with smaller length to width ratios of leaves, fruit and seeds, smaller sizes of fruit and seeds and mucronate seed apices. Principal Component Analysis of the closely related taxa, based on multiple morphological characters, further recognised two separated groups. One of them comprises R. tonkinensis and R. rubrinervis , the other merely includes all individuals from these distinct Hainan populations. Therefore, R. brachycarpa , based on these distinct Hainan populations, is here erected as a new species, distinctly different from its published relatives.